Personnel lift



Oct. 3, 1967 E. E. RASMUSSEN 3,344,885

PERSONNEL LIFT Filed May 2, 1966 5 Sheets-Sheet 1 wlEcJgcrERasmussen INVENTOR Oct. 3, 1967 E. E RASMUSSEN PERSONNEL LIFT Filed May 2, 1966 5 Sheets-Sheet VNN E EdgczrEPas mussen gen P Oct. 3, 1967 E. E. RASMUSSEN PERSONNEL LIFT 5 Sheets-Sheet 5 Filed May 2, 1966 INVENTOR Hgeni' EdgarE. Ra s mussen United States Patent 3,344,885 PERSONNEL LIFT Edgar E. Rasmussen, 4950 SW. Barbur Blvd, Portland, Oreg. 97201 Filed May 2, 1966, Ser. No. 546,753 6 Claims. (Cl. 182-16) This invention relates to personnel lifts, and more particularly to a mobile lift by which personnel may be elevated to desired working stations above the ground.

It is the principal object of the present invention to provide a personnel lift which is adjustable vertically, horizontally and rotationally with respect to a base, to accommodate the positioning of personnel at desired elevations above level or uneven ground, for painting and repairing buildings and other structures and for performing other tasks of maintenance, servicing and construction.

Another important object of this invention is the provision of a personnel lift of the class described which is mobile and highly maneuverable in confined spaces.

Still another important object of the present invention is the provision of a personnel lift of the class described which is of rugged construction, providing maximum safety in use, and is of simplified construction for economical manufacture.

The foregoing and other objects and advantages of this invention will appear from the following detailed description, taken in connection with the accompanying drawings in which:

FIG. 1 is a view in front elevation of a personnel lift embodying the features of the present invention;

FIG. 2 is a fragmentary foreshortened elevation, partially sectioned, of the upper portions of the telescoping booms;

FIG. 3 is a foreshortened side elevation as viewed fiom the left in FIG. 1;

FIG. 4 is a sectional view taken on the line 44 in FIG. 1;

FIG. 5 is a fragmentary sectional view taken on the line 5-5 in FIG. 4; and

FIG. 6 is a schematic diagram of an electric circuit for the control motors of the apparatus.

Referring to the drawings, the personnel lift of the present invention includes a rectangular main frame provided by the side frame members 8 and 10, rear frame member 12 and front frame member 14.

The main frame preferably is rendered mobile by support upon the two rear wheels 16, 18 and the two front wheels 20, 22. Further, in the preferred embodiment illustrated, these wheels are mounted such that they all constitute steerable wheels, and they are interconnected for simultaneous steering in a manner to provide the frame with minimum turning radius.

Accordingly, each wheel is supported upon an axle 24, supported between the spaced legs of a U-shaped yoke member 26. A pivot shaft 28 extends upward from the closed end of the yoke member and is journaled in a hearing mounted adjacent a corner of the main frame. Secured to the upwardly projecting end of the shaft of the rear wheel 16 is a sprocket 30. The projecting end of the shaft of the other rear wheel 18 mounts the two sprockets 32 and 34. In similar manner, the shaft mounting the front wheel 20 on the same side of the main frame that carries the shaft for the rear wheel 16, supports the sprocket 36, and the shaft of the front wheel 22 on the same side of the main frame as the shaft for the rear wheel 18 supports the two sprockets 38 and 40.

In the preferred embodiment illustrated, longitudinally adjustable turnbuckles 47 are interposed in the opposite stretches of each of the chains 42, 44 and 46. These serve to provide proper chain tension and also to adjust the wheels to proper alignment.

3,344,885 Patented Oct. 3, 1967 A continuous chain 42 engages and extends between the sprockets 30 and 32 at the rear of the main frame. A similar continuous chain 44 engages and extends between the sprockets 36 and 38 at the front end of the main frame. A third continuous chain 46 engages and extends between the sprockets 34 and 40 on the shafts of the rear and front wheels 18 and 22, respectively.

Idler sprockets 48, supported by the rear frame member 12 of the main frame, serve to guide the chain 42. Similar idler sprockets 50 on the side frame member 10 of the main frame serve to guide the chain 46.

The stretches of the chain 44 at the front end of the main frame, between the sprockets 36 and 38, engage a steering sprocket 52 mounted for rotation on the shaft 54 carried by the front frame member 14 of the main frame. An idler sprockets 56, mounted adjacent the steering sprocket, maintains the chain in positive engagement with the sprocket. A steering yoke member 58 is secured for rotation with the steering sprocket 52, and is adapted for releasable attachment of the steering lever 60, as by means of the connecting bolt 62. The projecting end of the steering lever may be provided with the socket component 64 of a conventional ball and socket trailer hitch, whereby the mobile frame may be connected to a powered vehicle for transport.

An auxiliary steering sprocket 66 is mounted for rotation on the shaft 68 carried by the side frame member 10 of the main frame, and this sprocket engages an intermediate portion of the chain 46 intermediate the sprockets 34 and 40. The auxiliary sprocket also is provided with a yoke member 58, substantially identical to the yoke member 58, for releasable connection of the steering lever 60. Manual steering of the mobile frame thus may be accomplished either from the front or side, as conditions of use dictate.

It is to be noted (FIG. 4) that the chain 46 is wrapped about the front sprocket 40 in the direction opposite its wrapping about the rear sprocket 34. It is by this means that rotation of either of the steering sprockets in one direction efiects rotation of the front wheel shafts 28 in the same direction, with simultaneous rotation of the rear wheel shafts in the opposite direction. By thus turning the front and rear wheels in opposite directions, the turning radius of the main frame is reduced to a minimum. The front and rear wheels may be turned to right angles relative to the longitudinal axis of the frame. This enables the frame to be manipulated with ease through confined areas and around sharp corners. This feature is of particular advantage when the personnel lift is used for painting the outside of a building where shrubbery and other obstructions would otherwise present problems in obtaining proper position.

The wheeled frame may be moved about by manual power, although it is preferred that a drive source be provided. In the embodiment illustrated, such source is provided by the electric motor 70 (FIG. 1) one associated with each of the front wheels. Each motor is mounted upon the supporting wheel yoke 26 and its output shaft 72 is connected to the associated wheel through the sprockets 74, 76 and chain 78.

The main frame supports within it a secondary frame formed of the side frame members 80 and 82, the rear frame member 84 and the front frame member 86. A central, longitudinal frame member 88 interconnects the rear and front frame members 84, 86 to reinforce the frame. This secondary frame is supported by the main frame for pivotal movement on the common transverse axis of the pivot pins 90 which mount the secondary frame on the main frame. Reinforcing braces 92 extend from under the rear corners of the secondary frame and converge forwardly beyond the front frame member 86 where I 3 they join a tongue member 94 which projects forwardly from said front frame member.

The bottom end of an elongated threaded adjustment screw 96 is connected to the projecting tongue 94 for rotation on its longitudinal axis and for limited pivotal movement on a transverse axis substantially parallel to the axis of the pivot pins 90. The elongated screw extends upwardly through a threaded collar 98 which is mounted at the upper end of the bracket 100. The collar is secured to the bracket against rotation but for limited pivotal movement, by such means as the transverse pins 102 the common axis of which is substantially parallel to the axis of the pins 90. An ofi'set handle 104 is secured to the projecting upper end of the screw to facilitate hand manipulation.

By means of the adjustment screw the secondary frame may be pivoted on the axis of the pins 90 relative to the main frame. The primary purpose of this adjustment is to maintain the secondary frame horizontal in the event the main frame is supported upon inclined or uneven ground which disposes the main frame in an inclined position in its longitudinal direction.

A circular turntable track member 110 is secured to the secondary frame with its center on the transverse axis of the pivot pins 90. Mounted upon and guided by this track member is a base which functions as a turntable. This base is constructed of the elongated crossed beams 112 and 114, and a pivot pin 116 interconnects these beams and the underlying central longitudinal frame member 88 of the secondary frame.

Adjacent the opposite ends of the beam 112 are secured the upstanding U-shaped supports 116. Each of these supports pivotally mounts the lower end of an elongated, hollow lower boom member 118, by means of the pivot pin 120. A transverse brace member 122 interconnects the spaced boom members 118 to stabilize the latter and to interconnect them for simultaneous pivotal movement about the common axis of the pins 120. In the embodiment illustrated, such pivotal movement is effected by means of the elongated screw 124 mounted for rotation in the elongated guide channel member 126 supported on the beam 114 of the base by the supporting brackets 128. The screw engages a threaded collar 130 on 'the adjustment bracket 132 which slidably engages the channel member for movement longitudinally thereof in either direction as the screw is rotated in the appropriate direction. The adjustment bracket 132 projects upwardly to intercept the cross brace 122, whereby to support the lower booms in various positions of angular adjustment. Projecting upwardly from the channel member 126 is a stop member 134 which intercepts the transverse brace 122 on the side opposite the adjustment bracket 132. The stop member is positioned to limit pivotal movement of the lower booms in the counterclockwise direction (FIG. 1) such that the booms always tend to rotate clockwise and thus always bear against the adjustment bracket, in any desired position of angular inclination.

Although the adjustment screw 124 may be rotated manually by such means as a hand crank, it preferably is rotated by the illustrated gear reduction unit and electric motor 136 secured to the channel member 116.

Slidable telescopically over each of the lower booms 118, over a substantial range of extension and retraction, is an elongated, hollow upper boom 138. Means for extending and retracting the upper boom relative to the lower boom is provided, in the embodiment illustrated, by 'the pair of cables 140 and 140', one associated with each boom assembly. Thus, one end of the cable 140 is secured to the lower end of an elongated post 142 which is secured at its upper end to a bracket 144 at the upper end of the upper boom. The post terminates at its lower end within and somewhat above the lower end of the upper boom. The cable extends upward from the post and is trained over a guide pulley 146 mounted for rotation within the lower boom at the upper end thereof. The cable then extends downward and out through the open lower end of the lower boom. The cable then passes around a guide pulley 148 mounted rotatably on the turntable beam 112, and its adjacent end is secured to the winch drum 150 (FIG. 5). The other cable is associated in identical manner with the other boom assembly, and its lower terminal end is secured to the same winch drum in such manner that both cables will be drawn in or payed out simultaneously upon rotation of the drum in the appropriate direction. The means for rotating the drum is described in detail hereinafter.

A personnel supporting platform 152 is mounted between the spaced boom assemblies for movement longitupdinally and transversely thereof. Thus, in the embodiment illustrated, the platform is secured adjacent its forward end, by such means as the pins 154, to the forward ends of a pair of laterally spaced, elongated, hollow rods 156. These rods are confined slidably within a pair of laterally'spaced channel guide members 158. Each guide channel member is open at its upper end, and a bolt extends between the spaced sides thereof across the upper side of the rod 156, to confine the latter removably in the guide channel member.

Each of the guide channel members is supported adjacent one of the boom assemblies for movement longitudinally thereof. Thus, a bracket 162 is secured at one end to the guide member adjacent the forward end thereof, and projects downward therefrom. The lower end of this bracket is connected by the pivot pin 164 to the forward end of the upper horizontal section 166 of a mounting bracket. The rearward end of this upper horizontal section joins the upper end of the vertical, intermediate section 168, and the lower end of this intermediate section joins the forward end of the lower horizontal section 170. A brace 168 interconnects the spaced intermediate sections 168. The rearward end of the lower horizontal section pivotally supports a projection 172 which is provided with a threaded transverse opening. This opening receives the elongated threaded rod 174 which projects vertically upward therefrom through an opening in a bracket 176 projecting laterally outward from the guide channel member 158 adjacent the rearward end thereof. A pair of spaced collars 178, secured to the rod 174 adjacent the upper end thereof, confines the bracket 176 between them, whereby the rod is held against axial displacement relative to the bracket but is permitted to rotate. The upper end of the rod is provided with an offset crank 180 to facilitate such rotation.

The upper and lower horizontal sections of the bracket each supports a pair of spaced guide wheels 182 which confine the associated boom assembly between them. The wheels of each pair are mounted upon shafts 184 which extend through horizontally elongated slots 186 in the associated bracket section and also through similar' ly elongated slots 186 in the connecting link member 188 disposed on the side of the boom opposite the bracket section. A resilient spring190 interconnects the shafts of each pair of wheels, at each end of the shafts. In this manner the wheels of each pair are mov able resiliently toward and away from each other to permit movement of the wheels across the juncture between the lower and upper booms. This arrangement also accommodates leveling of the platform to horizontal position by the adjustment rods 174 as the boom assemblies are adjusted to various angular positions.

Means is provided for moving the platform assembly along the length of the boom assemblies. In the embodiment illustrated, the lower ends of a pair of link members 192. are connected pivotally to the bracket sections 166 associated with both boom assemblies. Cables 194 and 194' are secured one to each link member.-Each cable extends upward over a guide pulley 196 mounted at the upper end of the upper boom, and thence downward along the side of the boom assembly and under a guide pulley 198 mounted on-the beam 112 of the turntable base. The cables then extend toward and are secured to the winch drum 200 (FIG. 5) in such manner that both of them are drawn in or payed out simultaneously upon rotation of' the drum in the appropriate direction.

The winch drum 200 is secured to the output shaft 202 of a gear reduction unit 204, the input of which is connected to the driven shaft of an electric motor 206. The gear reduction unit and motor are mounted upon a plate 208 secured to the beam 112 of the turntable base. The output shaft of the gear reduction unit also carries a sprocket 210 which is connected through the chain 212 to a sprocket 214 mounted freely on the shaft 216. A clutch unit 218 releasahly interconnects the sprocket 214 and shaft 216, and this shaft supports the winch drum 150 for rotation therewith. The shaft also supports a locking disc 220 for rotation therewith, and this disc is provided with a radial projection 222 which is adapted to be releasably engaged by the retractable stop pin 224 which is reciprocative in a sleeve 226 secured to the plate 208.

A lever 228 pivotally interconnects the upturned end of the stop pin 224 and the clutch unit 218 and is mounted on the pivot 230 projecting from the plate 208 for pivotal adjustment to the positions determined by the stop lugs 232 and 234 (FIG. 4). Thus, upon movement of the lever in one direction the stop pin is retracted from the path of the projection 222 and the clutch unit is moved to engage the sprocket 214 with the shaft 216. Conversely, when the lever is moved in the opposite direction the clutch unit is moved to disengage the sprocket 214 from the shaft 216 and the stop pin 224 is moved to intercept the projection 222.

It is to be noted that when the upper boom 138 of each boom assembly is moved relative to the lower boom 118, with the platform 152 remaining in fixed position relative to the upper boom, the amount of cable 140, 140' taken up or payed out from the winch drum 150 must be one-half the amount of cable 194, 194' payed out from or taken onto the drum 200. Accordingly, the sprocket 214 associated with the drum 150 is twice the size of the sprocket 210 associated with the drum 200.

With the clutch unit engaged and the stop pin 224 retracted, both drums are rotated simultaneously. With the clutch unit disengaged and the stop pin extended to intercept the projection 222, the sprocket 214 rotates freely on the shaft 216 while its associated drum 150 is secured against rotation. Operation of the motor 206 thus enables the platform 152 to be moved vertically along the boom assemblies without moving the upper boom 138 relative to the lower boom 118.

Means also is provided for moving the platform 152 transversely between the boom assemblies. In the embodiment illustrated, such means is provided by the synchronous electric motors 236 one mounted on each of the spaced channel guide members 158. The output shaft of each motor carries a gear 238 which extends through an opening 240 in the channel guide member and engages the rack teeth 242 provided along the length of the rod 156.

A resiliently surfaced roller 244 is mounted at the upper end of each of the upper booms 138, on a bracket 246 which may also support the pulley 196. The roller projects laterally therefrom in the direction in inclination of the boom assemblies. These rollers thus are disposed for rolling engagement with a vertical wall W or other structure, to provide support for the upper ends of the boom assemblies. A similar wall engaging roller 248 is mounted on the forward end of each of the rods 156 for cooperation with the rollers 244, to enhance the stability of the lift assembly.

An upstanding wall 250 may be provided at the rearward side of the platform 152 as protection against falling from the latter. Stabilizing rods or cables 252 may be employed to interconnect the platform and the rear wall to stabilize the latter.

FIG. 7 illustrates electrical circuitry for controlling the various electric drive motors. Thus, the drive wheel motors 70 are connected through the reversing switches 254 and 254 to the terminals 256 of a source of electric supuply. The electric motor 136 for controlling the angular position of the boom assemblies is connected preferably through the pair of reversing switches 258 and 260, arranged in parallel, to the supply terminals. The electric motor 206 for controlling the vertical extension and retraction of the boom assemblies and platform is connected through the pair of reversing switches 262 and 264, arranged in parallel, to the supply terminals. The pair of electric motors 236 for controlling the horizontal adjustment of the platform 152 are connected through the pair of reversing switches 266 and 268, arranged in parallel, to the supply terminals.

The reversing switches 254 and 254 for the drive wheel motors and one of each of the pairs of switches, for example switches 258, 262 and 266 for the other drive motors, are mounted adjacent the outer end of the steering lever 60 for convenient manipulation. An electrical connector is mounted adjacent each of the steering sprockets 52 and 66 for connecting these switches into the associated electric circuits for either position of the steering lever 60. The other switches of the pairs, namely switches 250, 264 and 268, are mounted on the protective wall 250 at the rearward end of the platform 152, for convenient manipulation by the person carried on the platform. V

In the following description of operation of the personnel lift, let it be assumed it is desired to employ the lift for painting the outside wall of a building. While steering the vehicle, the operator manipulates the reversing switches 254 and 254' to drive the wheels in the appropriate direction to manipulate the vehicle into proper position adjacent the building wall. In the event the vehicle thus positioned is on inclined or uneven ground, so that the vehicle frame is inclined in its longitudinal direction, the operator manipulates the crank handle 104 in the proper directionto bring the secondary frame to horizontal position. Further, if the main frame is not disposed square to the building wall, the operator may apply manual force to the turntable assembly to pivot the latter and the supported boom assemblies and platform to properly aligned position with respect to the wall.

Assuming the platform 152 is in its lowermost position of adjustment and it is desired to extend the upper booms 138, the operator pivots the lever 228 to the position in which the clutch unit 218 connects the sprocket 214 to the shaft 216 and the locking pin 224 is retracted from the locking projection 222. The operator then manipulates the reversing switch 262 to energize the electric motor 206 in the direction to wind in the cables 140, 140 on the drum 214, thereby causing the upper booms to extend. Simultaneously with this action the drum 200 rotates to pay out twice the length of cable 194, 194' as the length of cable being wound in on the drum 214. Accordingly, the platform 152 remains in its lowermost position while the upper booms extend.

The operator now pivots the lever 228 to a position in which the stop pin 224 is extended to intercept the lockmg projection 222 and the clutch unit 218 disengages the sprocket 214 from the shaft 216.

Having extended the booms to the desired height, the operator now may enter upon the platform 152. If the platform is not level, he manipulates the crank to rotate the threaded rods 174 in the appropriate direction to pivot the platform assembly about the pivot pins 164 until the plafotrm is brought to level condition.

The operator now manipulates the reversing switch 264 to energize the electric motor 206 in the direction to wind in the cables 194, 194 on the drum 200. The platform assembly thus is pulled upward along the boom assemr v 7 blies until the desired elevation above the ground is reached. p

Assuming that the forward end of the platform previously had been retracted to its rearwardmost position, the operator now manipulates the reversing switch 268 to energize the electric motors 236 in the direction to move the platform forwardly until the rollers 248 engage against the building wall. The apparatus now is in properly adjusted position for commencement of painting the building wall.

It will be apparent to those skilled in the art that various changes in the number, size and arangement of parts described hereinbefore may be made without departing from the spirit of this invention and the scope of the appended claims.

Having now described my invention and the manner in Which it may be used, what I claim as new and desire to secure by Letters Patent is:

1. A personnel lift comprising (a) a frame,

(b) a turntable means mounted on the frame for rotation on a substantially vertical axis and for pivotal movement on an axis normal to said vertical axis,

() a pair of longitudinally adjustable, laterally spaced telescoping booms mounted at their lower ends on the turntable means for pivotal movement on an axis parallel to the plane of the turntable means,

(d) platform mounting means supported between the booms for movement longitudinally thereof and having a platform engaging section and a boom engaging section adjustable relative to each other,

(e) adjustable leveling means interengaging the sections of the platform mounting means for adjusting the platform engaging section to horizontal position, andv (f) a platform supported on the platform engaging section and between the booms for movement transversely of the latter.

2. The personnel lift of claim 1 including drive means interengaging the platform and platform engaging sections for moving the platform relative thereto.

3. The personnel lift of claim 1 including (a) a plurality of steerable wheels on the frame, (b) a vertically disposed shaft mounting each steerable Wheel on the frame, 7

(c) a sprocket on each shaft, w

(d) drive chain means engaging the sprockets, and

(e) a steering sprocket mountedon the frame and engaging the chain means. 4. A personnel lift of claim 3 wherein the steerable wheels comprise a pair of front wheels and a pair of rear wheels, and the drive chain means engages the sprockets in such manner as to cause the front and rear wheel mounting shafts to rotate in opposite directions.

5. The personnel lift of claim 3 wherein (a) the steerable wheels comprise a pair of front wheels and a pair of rear wheels, p

(b) the drive chain means comprises a pair of chains one of which engages the sprockets on the shafts mounting the front wheels and the other of which engages the sprockets on the shafts mounting the rear Wheels,

(c) a connecting sprocket is secured to one of the shafts associated with each of the chains, and

((1) connecting chain means engages the connecting sprockets in such manner as to cause the front and rear wheel shafts to rotate in opposite directions.

6. The personnel lift of claimi including (a) an auxiliary steering sprocket associated with the connecting chain means,

(b) a control lever, and

(0) connecting means on each steering sprocket for securing the control lever selectively thereto.

References Cited UNITED STATES PATENTS 107,225 9/1870 Claflin 182-103 2,249,900 7/1941 Honig 182103 2,394,148 2/1946 Campbell 182-103 3,095,945 7/1963 Mitchell 182l6 3,178,048 4/1965 Bergman 182-103 RENALDO P. MACHADO, Primary Examiner. 

1. A PERSONNEL LIFT COMPRISING (A) A FRAME, (B) A TURNTABLE MEANS MOUNTED ON THE FRAME FOR ROTATION ON A SUBSTANTIALLY VERTICAL AXIS AND FOR PIVOTAL MOVEMENT ON AN AXIS NORMAL TO SAID VERTICAL AXIS, (C) A PAIR OF LONGITUDINALLY ADJUSTABLE, LATERALLY SPACED TELESCOPING BOOMS MOUNTED AT THEIR LOWER ENDS ON THE TURNTABLE MEANS FOR PIVOTAL MOVEMENT ON AN AXIS PARALLEL TO THE PLANE OF THE TURNTABLE MEANS, (D) PLATFORM MOUNTING MEANS SUPPORTED BETWEEN THE BOOMS FOR MOVEMENT LONGITUDINALLY THEREOF AND HAV- 